Collapsible control stick for airplanes



Feb. 10, 1942 J. E. PALMER COLLAPSIBLE CONTROL STICK FOR AIR PLANES Filed Dec. 4, 1939 Patented Feb. 19, 1942 COLLAPSIBLE CON w i I PLAN S TROL STICK FOR John E. Palmer, Reading, Mass.

Application December 4, 1939, Serial No. 307,351

Claims.

This invention relates to airplanes provided with double control means for the elevator planes and ailerons used for the instruction of student aviators. The control lever or arm for this purpose is commonly called a joy stick and will be so called in this description. The planes used for instruction are equipped with tandem cockpits or seats, of which the forward one is occupied by the instructor and the rear one by the pupil. A joy stick is provided in the proper relation to each seat, and both sticks are coupled to the same controls in a manner such that when either stick is moved in any manner, the other stick is equally moved in the same manner. Conversely, if either stick is prevented from moving, as by the rigid grasp and clutch of the student flier, resulting from panic fear, the other stick cannot be moved and the plane may pass out of control.

It is the object of this invention to provide a joy stick for the use of the student which is in efiect breakable or collapsible, and the collapse of which may be caused instantaneously by the instructor whenever necessary. It is a further object to provide means by which the pupils joy stick, after having been rendered inoperative by the instructor, may be again put into operative condition without necessity of first landing or of depending on cooperation by the pupil. A further object is to provide means for the purpose indicated which are equally effective with joy sticks having one or more curves or bends in them as with wholly straight sticks; and which will permit free tilting of the handle end of the stick through a practically unlimited angle in any direction when the stick is put into the broken or collapsible condition.

In the drawing furnished herewith to illustrate the invention Fig. 1 is a diagrammatic view which illustrates the general relationship to each other of the seats and joy sticks used by the instructor andpupil in an airplane with tandem controls;

Fig. 2 is a longitudinal sectional view of a joy stick embodying the invention;

Fig. 3 is a sectional view on a larger scale of the joint and adjacent parts of my collapsible joy stick;

Fig. 4 is a cross section on line i4 of Fig. 3.

Like reference characters designate the same parts wherever they occur in all the figures.

Referring first to Fig. 1, the seat occupied by the instructor in a tandem two seater plane is indicated at a and the instructors joy stick at b. The rear seat, occupied by the pupil, is indicated at c and the pupils joy stick at d. This figure 55 tration into each to hold the parts rigidly in' also shows in a general way connections between the two joy sticks and the controls for the elevator planes and ailerons, which are not a part of the present invention and need not be described. This invention resides wholly in characteristics of the joy stick at provided for use by the pupil and which, otherwise, may be of any suitable character and connected to the control vanes by any suitable means.

This joy stick consists of two separate portions, namely, a lever portion I and a handle portion 2, each sufiiciently rigid to provide the necessary stiffness in the stick when coupled together in the manner presently described. The

lever portion includes means, such as lugs 3 and.

t, by which it may be mounted on a fulcrum pivot and connected with the controlling members of the airplane. The last named means shown here are illustrative merely and may be of any other character suitable for any type of installation.

The said lever portion and handle portion are tubular and are adapted to abut against one another at their adjacent ends. Blocks 5 and 6 are fitted and secured in the adjacent ends of the tubes, one of the blocks preferably being set back from the extremity of the tube to form a shallow socket I, and the other being extended and formed to enter such socket and assist in centering and alining the tubes when permitted to occupy alining positions.

Flexible wires 8 and 9 pass from an anchorage ID in one of the tubes through passages I I, I2 in the block 5 and through passages I3, I4 respectively in the block 6. These passages are enough larger than the wires to permit free movement and prevent binding of the wires in them. The ends of the wires in the handle portion 2 are connected to the hooked ends of helical springs I5 and I6 respectively, which are anchored to a cross bar IT. A bolt I8 is adapted to occupy, and fit closely but with freedom to slide endwise in, passages I9 and 20 in the blocks. The end of the bolt which is adapted to enter the handle portion is connected to a spring 2I which also is anchored to the bar IT. A flexible cord or Wire 22 is made fast to the end of the bolt within the lever portion I and extends through a guide 23 near the fulcrum point, out through the side of the tube I and forwardly to a position such that a handle 24 on its extremity may be conveniently grasped and pulled by the instructor..

The normal condition of the stick is that shown in Fig. 2, where the bolt is held by spring 2! in the passageways I9 and 26, with suificient penealinement, or with sufficient rigidity to enable the student pilot to control the plane. The movement of the bolt under the pull of the spring may be limited by a pin 25 passing through it and projecting at both ends to be arrested by the inner end of block 5. In the event of the student losing self-control through panic, so that he freezes to the stick, as the saying is, the instructor may withdraw the bolt by pulling on the cord 22. The handle portion is then released from the lever portion, which enables the instructor to regain control.

The connection afforded by the flexible wires 8 and 9 and the springs I5 and I6 is sufficiently pliable and yielding to permit the lever portion to follow the movements of the instructors stick even though the student may hold the handle with all his strength. But if, while the plane is still in the air, the student recovers his wits and releases the handle, the latter is automatically 1 restored into alinement with the lever portion, by the springs I5, 16 and 2! with the aid of the centering socket l, whereupon the instructor may release the bolt and permit it automatically to make the students stick rigid again. It is noteworthy that the bolt-projecting spring cooperates with the tensioned wires in alining the parts of the stick.

In order to resume instruction and restore control to the pupil, it is only necessary for the pupil to release the stick and the instructor to release the bolt retracting line. The springs then automatically return the handle to its alined and coupled connection with the lever portion. No

positive action on the part of either instructor or pupil is needed to effect this result.

By virtue of the flexible spring-tensioned tie members (the wires 8 and 9), the handle portion, after retraction of the bolt, may be tilted in any direction through an angle of more than 90, and it will be automatically restored to alinement with the lever portion when released. Two wires equidistant from the axis and at diametrically opposite sides are preferably used, to equalize and balance the pull of the springs. It is possible, however, to use only a single connecting wire axially located in the stick and to mount the bolt at one side of the axis, within the scope of the invention. However, the arrangement shown is preferred. It may be desirable, and preferable for some purposes, to provide three or more wires and tension springs, suitably distributed around the axis to give the desired centralized balanced pull; and this also is within the scope of the invention.

The bolt and the receiving blocks may be located at any desired point in the length of the stick and the break made at the same point. These parts may be located in a curved or bent stick, such as that shown for illustration in Fig. 1, wherever there is a straight or nearly straight portion sufficiently long to accommodate the bolt and its receiving passages. No great length is needed for this purpose. A length in the order of four or five inches is sufficient.

In the construction here shown, the stick is made of two sections of metal tubing with metal blocks set and secured in their abutting ends and with a fulcrum fitting at one end and a knob at the other end for giving a finished appearance. But various alternative modes of construction and structural details are feasible within the scope of thi invention. For instance, the blocks may be integral with the tube walls.

What I claim and desire to secure by Letters Patent is:

1. A control stick for airplanes consisting of two substantially rigid tubular sections, a block in one end of each section, one of said blocks being located within the end of its section to provide a shallow socket, and the other block extending from its section and being adapted to enter said socket and center the sections in alinement with each other, said blocks being formed with alined passageways extendin lengthwise of the stick, a flexible tie member passing freely through certain of said passageways and being anchored in one of said sections, a spring anchored in the other section and connected to said tie member in a manner to exert tension thereon, a bolt slidably occupying other or said alined passageways, and means external to the stick in coupled connection with said bolt for withdrawing it.

2. A control stick for airplanes consisting of two tubular sections, a block in one end of each section, one of said blocks being located within the end of its section to provide a shallow socket, and the other block extending from its section and being adapted to enter said socket and center the sections in alinement with each other, said blocks having alined passageways extending lengthwise of the stick, a flexible tie member passing freely through certain of said alined passageways and being anchored in one of said sections, a spring anchored in the other section and connected to said tie member in a manner to exert tension thereon, a bolt slidably occupying other of said alined passageways, means external to the stick in coupled connection with said bolt for withdrawing it from one of the blocks, and a spring Within the stick connected with the bolt to project it into the described locking relationship.

3. A control stick for airplanes consisting of a tubular lever section having a block in one end, a tubular handle portion having a block in one end, one of said blocks being inset to provide a socket and the other block being extended to enter said socket for centering the handle por tion in alinement with the lever portion, said blocks being formed with alined passageways extending substantially parallel with the length of the stick, flexible tie members anchored in the lever portion extending through certain of said alined passageways in both blocks into the handle portion, springs anchored in the handle portion connected with said tie members to apply tension thereto, and a retractable spring projected bolt extending from one block to the other in other alined passageways in the two blocks to which the bolt is slidingly fitted.

4. A control stick for airplanes consisting of a tubular lever section having a block in one end, a tubular handle portion having a block in one end, one of said blocks being inset to provide a socket and the other block being extended to enter said socket for centering the handle portion in alinement with the lever portion, said block having alined passageways extending lengthwise of the stick, flexible tie members anchored in the lever portion extending through certain of said passageways in both blocks into the handle portion, springs anchored in the handle portion connected with said tie members to apply tension thereto, a bolt fitted slidingly in other passageways in said blocks, a spring anchored in the handle portion and connected to the adjacent end of the bolt normally holding the bolt in a position where it occupies the socket passageway in both blocks, and a retracting line connected to the opposite end of the bolt and extending from the lever portion to a distant control point.

5. A control stick for airplanes consisting of a lever section and a handle section in separable end abutting relationship with each other, each section being a tube with a thick end wall at the end contiguous to the other section, said end walls having alined passageways opening to the interior of the respective sections, a flexible tension member anchored in one section and passing through alined passageways in both said end walls, a spring anchored in the other section connected to said tension member to apply yieldable resilient tension thereto, a bolt passing through and fitting retractably in alined passageways in both the end walls, a spring anchored in one of said sections connected to the nearer end of the bolt arranged to exert a pull thereon when the bolt is retracted from the end wall of the section in which said last-named spring is anchored, and a retracting element connected to the bolt and operable at a distant point to withdraw the bolt from the section last referred to.

JOHN E. PALMER. 

